TY - JOUR
T1 - Galaxy and mass assembly (GAMA): AUTOZ spectral redshift measurements, confidence and errors
AU - Baldry, I.K.
AU - Alpaslan, M.
AU - Bauer, A.E.
AU - Bland-Hawthorn, J.
AU - Brough, S.
AU - Cluver, M.E.
AU - Croom, S.M.
AU - Davies, Luke
AU - Driver, Simon
AU - Gunawardhana, M.L.P.
AU - Holwerda, B.W.
AU - Hopkins, A.M.
AU - Kelvin, L.S.
AU - Liske, J.
AU - López-Sánchez, A.R.
AU - Loveday, J.N.
AU - Norberg, P.
AU - Peacock, J.A.
AU - Robotham, Aaron
AU - Taylor, E.N.
PY - 2014/7/1
Y1 - 2014/7/1
N2 - The Galaxy And Mass Assembly (GAMA) survey has obtained spectra of over 230 000 targets using the Anglo-Australian Telescope. To homogenize the redshift measurements and improve the reliability, a fully automatic redshift code was developed (AUTOZ). The measurements were made using a cross-correlation method for both the absorption-and the emission-line spectra. Large deviations in the high-pass-filtered spectra are partially clipped in order to be robust against uncorrected artefacts and to reduce the weight given to single-line matches. A single figure of merit (FOM) was developed that puts all template matches on to a similar confidence scale. The redshift confidence as a function of the FOM was fitted with a tanh function using a maximum likelihood method applied to repeat observations of targets. The method could be adapted to provide robust automatic redshifts for other large galaxy redshift surveys. For the GAMA survey, there was a substantial improvement in the reliability of assigned redshifts and in the lowering of redshift uncertainties with a median velocity uncertainty of 33 km s-1. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
AB - The Galaxy And Mass Assembly (GAMA) survey has obtained spectra of over 230 000 targets using the Anglo-Australian Telescope. To homogenize the redshift measurements and improve the reliability, a fully automatic redshift code was developed (AUTOZ). The measurements were made using a cross-correlation method for both the absorption-and the emission-line spectra. Large deviations in the high-pass-filtered spectra are partially clipped in order to be robust against uncorrected artefacts and to reduce the weight given to single-line matches. A single figure of merit (FOM) was developed that puts all template matches on to a similar confidence scale. The redshift confidence as a function of the FOM was fitted with a tanh function using a maximum likelihood method applied to repeat observations of targets. The method could be adapted to provide robust automatic redshifts for other large galaxy redshift surveys. For the GAMA survey, there was a substantial improvement in the reliability of assigned redshifts and in the lowering of redshift uncertainties with a median velocity uncertainty of 33 km s-1. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
UR - https://www.scopus.com/pages/publications/84903187998
U2 - 10.1093/mnras/stu727
DO - 10.1093/mnras/stu727
M3 - Article
SN - 0035-8711
VL - 441
SP - 2440
EP - 2451
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -